Problem with keyframes
Maybe what you need to do is create a root bone that will allow you to move your robot up and down while its spine will rotate:


In Edit mode, create a root bone. Make it the parent of the spine basis (and also of all the IK controllers, pole targets, etc...).
In the Properties panel > Bone > disable the Deform option so that this kind of bone (like IK controllers, pole targets...) won't have any influence on the mesh.
Now you can independently rotate the spine basis and move the root up and down.


Another way could be to move the armature in Object mode, but the best, if your robot stay rather still on the scene, is to create a root bone so that the armature (as an object) remains not animated.

But when you'll make your robot move along a path, most of the time you'll use this second option, though.